A vehicle speed controller is known from German Published Patent Document No. 28 42 023 (U.S. Pat. No. 4,337,511), in which the driving speed of the vehicle is adjusted as a function of a driving speed setpoint value predetermined by the driver. The output signal of the vehicle speed controller acts on a power controller for the vehicle engine. Depending on the design, the vehicle speed controller itself exhibits proportional, integral, and/or differential response. To improve the dynamic response of the controller in a control process which causes a change in driving speed, such as an actuation of the acceleration key, the setpoint value of the vehicle speed control is set to the value of the actual speed measured upon actuation of the key plus a fixed offset value, and change of the vehicle speed is implemented by ramp-shaped changing of the setpoint value. When the speed intended by the driver is reached, the offset value is canceled and the control is then performed based on the setpoint value present at that time.
The above-described procedure improves the dynamic response of the vehicle speed controller for a control process which increases the vehicle speed (acceleration, resumption of speed). For vehicle speed controllers, however, considerable attention must be paid to the comfortable and accurate settling of the vehicle speed at the setpoint value after such a dynamic control process has concluded.
In this connection, German Published Patent Document No. 37 03 645 (U.S. Pat. No. 4,884,203) describes the approach that when the dynamic process (an acceleration process, for example) is completed, an actuating signal is offset by a predetermined amount, and this actuating signal is then reduced according to a time curve until the acceleration of the vehicle is zero. The jump-like response of the actuating signal results, at least in many cases, in reduced comfort. Furthermore, this approach has disadvantages in its application complexity.